VO Studio Gear: Three Thoughts About Shotgun Mics

Shotgun microphones are cool. They are the epitome of minimalism, sleek and simple. 

It’s been interesting to see how many voice actors have added them to their home recording setups as they work to improve their sound. There are good reasons to do this. Shotgun mics tend to be highly directional, rejecting off-axis sounds, so they could potentially solve issues related to noisy spaces or less well treated rooms. 

While this is true to some degree, it won’t work to just stick one in the middle of your tiled kitchen and hope it sounds stellar. If you work next to a steam shovel factory, it’s unlikely the mic alone will fix an issue with high levels of environmental noise. I certainly notice how the noise floor in my booth lowers when using the 416 versus my Mojave, however a weed whacker revving outside my window will bleed into either. 

I say that just to balance claims encountered in some of the forums, or in certain videos. A shotgun mic won’t necessarily solve your noise issues. In fact, some of the less expensive models that are purported to sound “just like…” the Sennheiser MKH416 have both a wider pickup pattern and do a less efficient job of cancelling off-axis sounds.

Those Fins Don’t Just Look Sporty

The off-axis rejection occurs because the microphone capsule (which is technically a small diaphragm condenser type) is located at the far end of an interference tube. That’s what gives them their characteristic shape. 

If you look at the side of the microphone, you’ll see a series of cuts on opposing sides of the tube. Generally these are vertical slashes which are “paired” so that the same shape occurs on both sides of the microphone. This is the interference tube section of the shotgun microphone. This lets sounds enter at a very specific angle, which allows the waves to cancel themselves out, removing errant signals from the audio input.

If a sound enters from only one side of the tube, it will tend not to cancel out. Which means that if you have a recording setup where there is noise only from your right or left, having the fins at 3 o’clock and 9 o’clock is not optimal. In that situation, I would rotate the microphone 90 degrees, to see if I can gain cancellation of the sound source from the side. When the ambient noise is complex, working to find an ideal rotation can help a great deal.

(This differs from the way that a Figure 8 pickup pattern acts in a Large Diaphragm Condenser microphone, which relies upon the capsule itself).

Shotgun Mics Are Not Bats 

So how come so many folks are hanging them nearly straight down from the ceiling? 

When shotgun microphones are found in their native environments, on film location sets, they are positioned using a long boom arm by the sound person. That enables the audio team to direct it at the actor who is speaking. Keep in mind that the microphone is normally several feet away from the source. That down-from-the-heavens angle is not needed when we move the mic into our recording space and address it from a much closer distance.  

I’ve been encountering a lot of voice actors who are running their shotgun mics at excessively steep angles – 45 degrees or even steeper. One of the reasons offered is that it might reduce plosives or mouth noise. I’ve never found that to work very well, as the resultant audio can sound muffled with a thin, crisp upper end. 

Shotgun mics are addressed from the end. Since the pickup pattern is narrow, this means a strong angle is generally less than optimum. The more steeply angled they are positioned, the more you will be speaking at the side of the mic, with the mic “hearing” sounds from where ever it is pointing.

My go-to position for a shotgun is to start with the microphone level and raise it to eyebrow-ish height. Then I angle it down so it’s aiming generally at my chin when I’m 4 to 8 inches away from it. This keeps me talking into the end of the mic, but moves it slightly up so I’m not talking directly into the tube. 

Minor Mic Modifications Matter 

Bringing a shotgun microphone into the smaller spaces common in home voiceover recording setups means minor changes in position will often make a big difference. The narrowest part of the pickup pattern occurs close to the mic, which is where we will be speaking. The sound that hits the interference tube should be balanced reasonably well between the fins, so adding a large screen or other reflective surface inside of your recording space can cause issues. Interestingly, most shotgun microphones have a fairly active pickup node at 180 degrees, so the surface and clearance behind the microphone can impact the sound quality as well. 

Position at the mic matters as well. Compared to a Large Diaphragm Condenser, the MKH416 and Rode NTG-5 tend to have a bit less proximity response. Since the capsule is already roughly 8 inches away at the far end of the interference tube, we may find that a seemingly close position can be effective. 

As with all of this stuff, the voice, the power of delivery, and the specifics of the recording space matter. Taking time to isolate those variables, then comparing the results on a known script, balanced for volume, would always be recommended. 

It all comes back to trusting our ears. Hearing the results, or having someone listen and provide feedback, is key to making that shotgun microphone sound good in your recording space. 

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